Blastocystis sp. frequency and sources among children from 0 to 5 years of age attending public day care centers in Calarcá, Colombia

There are no reports of the potential sources of Blastocystis sp . in Colombia. To estimate the frequency of Blastocystis sp . and explore possible associations among infection, clinical manifestations and environmental sources. A descriptive study was conducted; a representative sample was calculated from a population of 1,993 children less than 5 years old of the lowest socioeconomic levels (1 and 2) attending day care centers in Calarcá, Colombia. The calculated sample size was 275 children, who were selected randomly in 10 % of the centers. Stool testing, questionnaires and sampling to identify the parasite in feces, nails, pets and environmental sources, were performed. Fresh preparations were made with 1% iodine solution, and a concentration technique with formalin-ether was used. Prevalence and odd ratios were estimated; the chi-square test was utilized for qualitative variables, and Student's t for the quantitative ones. The prevalence of infection in children was of 57.5%. A statistically significant association was found between the Blastocystis sp . positive stool tests and the presence of the parasite in containers of sugar cane beverage (OR=1.70; 95% CI: 1.05-2.79), wood or ground floors (OR=3.43; 95% CI: 1.12-10.48) and in foods other than bottled milk (OR=3.23; 95% CI: 1.41-4.41). A non-significant high prevalence was found in nails (OR=1.62; 95% CI: 0.99-2.67), as well as a significantly higher prevalence of diarrhea (OR=1.95; 95% CI: 0.99-2.77) in children with Blastocystis sp . (45%) as compared with those without the parasite (33%; p